Delete the transition mixin. Autoprefixer will take care of prefixes

Autoprefixer will be added later
Delete transformation mixins
Delete unused column mixins
Remove hyphenation mixin and let Autoprefixer take care of it
Remove mostly unused Flexbox mixing
Allow components to change the border-box more easily and remove the mixin
Remove radial gradient in Colorbox overlay as it almost can't be seen anyway
Remove gradient mixins and let Autoprefixer take care of it
Less variables: Don't calculate font size, just set them
Rename the heading font size variable to match the others
Reorder font size variables to they are largest to smallest
Remove title mixing as they're only used once
Remove ::selection mixin as it's unused
Better Less structure - part 1

All base styles moved to their own files in the new base/ folder.
Update style.dev.less to reflect structure changes